The high-profile first-degree murder trial of Ian Bush continued Monday with more testimony from the lead forensic biologist in the case.

Bush, now 61, was charged in February 2015 with three counts of first-degree murder in the 2007 deaths of retired tax judge Alban Garon, his wife Raymonde Garon, and their friend and neighbour Marie-Claire Beniskos.

Their bodies were found in the living room of the Garons' luxury condo on Riverside Drive.

Bush has pleaded not guilty, and his trial before a judge and jury is expected to last 12 weeks.

In court Monday, Crown prosecutor James Cavanagh concluded his examination of Brian Peck, the lead forensic biologist in the triple homicide, who authored 24 reports in the case.

Peck testified that a number of items from a satchel found in Bush's home were tested for blood and DNA, including the handle of the bag, the handle of a heavy black metal bar, a pair of safety glasses, and the inside of a pair of yellow dish gloves.

Analysis showed that Bush couldn't be excluded as the source of DNA found on the inside of the dish gloves and the handle of the metal bar. The probability that a randomly selected person unrelated to Bush would coincidentally share the same DNA profile is about one in 13 quintillion, Peck told court.

Last week, Peck also testified there was about a one in 13 quintillion chance a randomly selected person unrelated to Bush would share the same DNA profile from a body hair found on the living room floor where the bodies were found.

The defence has admitted in court that the body hair does in fact belong to Bush.

The likelihood a randomly selected person unrelated to Bush would coincidentally share the same DNA profile found in a swab of mixed blood also found at the scene, however, is estimated to be higher: about one in 13,000, Peck said.

Defence questions biologist's comments

Peck testified last week that the most plausible explanation for both samples of DNA being found in the room was a "primary transfer" from its owner directly to the scene. And it's more incriminating, he told court, that both samples were found in the same place.

Under cross-examination Monday, assistant defence lawyer Martin Reesink asked Peck whether it was "in the realm of non-science" to make the primary transfer comment.

Peck told court that no, it was in the realm of science. The more transfers there are, he told the jury, the less DNA is present.

While it's possible for DNA to be picked up and transferred by people or things it doesn't belong to, there's a low chance of someone's DNA showing up in a room they've never been in before, he testified — and an even lower likelihood of two types of DNA samples being found in a room they've never been in before.

Reesink also asked whether Peck knew exactly how far apart the body hair and blood were at the crime scene. Peck said he didn't know, but an exact measurement doesn't matter — they were both found in a closed and private residence.

Peck also reiterated he can't determine when or how DNA ends up anywhere.